July 4, 2017 at 9:39PM

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EF Lens Aperture Issue With GH5 and Metabones Speedbooster

I recently upgraded to a Panasonic GH5 from a Canon 60D. I also bought the Metabones Speedbooster XL because I have full frame EF Canon lenses. The issue that I am having is that when I use my EF lenses with the Speedbooster (firmware is up to date), I can only stop down to f/14 on the Panasonic GH5 whereas I can stop all the way down to f/22 on the Canon 60D. Is anyone else having this issue or I am doing something wrong? Thanks in advance for any suggestions.

2 Comments

This might have been done intentionally by Metabones because ANY lens on a Micro 4/3 camera becomes "diffraction limited" after f/8.0. This means the image starts to lose sharpness once you close down more than f/8.0.

I normally never use apertures smaller than f/8.0 with my GH5 camera because of this, and will start to use ND filters if the lighting is too bright. ( for still photos you can just raise the shutter speed )

Also, in terms of Depth of Field f/8.0 on a Micro 4/3 camera is the SAME as f/16.0 on a Full Frame camera. So f/14 has the SAME DOF as f/28 on a Full Frame camera.

Hey, in case you haven't found out another way here's what's happening - because the Speed Booster XL accurately adapts the actual f-stop after conversion(and even shows it to you on the camera properly), the f/22 you are used to seeing is actually represented as f/14 once you add the 1 and 1/3rd stop increase the Speed Booster is giving the lens. This is why, when you look at the other end of the f-stop range on your lens, you see the f/4 automatically converted to f/2.5, f/2.8 to f/1.8, f/1.8 to f/1.1(if my memory serves) and so on. Thus, your lens is ultimately still stopping down all the way to f/22... it just gets converted as it passes through the Speed Booster.

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